No you can't keep it from moving, they do what they want to do when they want to do it, the only thing you can do is watch, if you do not want it in a certain area you need to be prepared to protect what is in that area in case it wants to go there.
Although there are many post about anemones stinging and killing other corals, I have found this to be not entirely true, I have a huge green leather and numerous zoos than are in contact with my anemone most of the time and other than closing up while they touch each other all seem to do just fine. As for your suction the only thing you can do it cover that with something to protect the anemone from getting caught in it. Good research before a purchase is the best way to protect your wallet and all tank inhabitants.